Bituminous coating material and a process for producing a bituminous coating on a support

ABSTRACT

A bituminous sheet or web coating material (1) is on the one side provided with a heat activatable adhesive layer (3) optionally covered by a plastic film (5), wherein the adhesive layer is provided with a pattern of close grooves (4) with intermediate unbroken ridges, and a process for forming a coating on a support is performed by heating such coating material (1) to decomposition of said plastic film (5) and activation of the adhesive layer (3), the activated adhesive layer (3) being pressed against the support, e.g. a roof.

BACKGROUND OF THE INVENTION

Present invention relates to a bituminous coating sheet materialprovided on one side with a heat-activatable adhesive layer that isoptionally coated with a plastic film.

In particular, the invention relates to a bituminous sheet-formedcoating material for the formation of a roof covering. It is known toproduce roofings by using roofing felt sheets, i.e., bituminous feltlengths, which are coated with a plastic film of, e.g., polyethylene orpolypropylene, having a thickness of about 10 μm.

The main function of the plastic film is to prevent adjacent parts ofthe roofing felt sheets from sticking to each other when the sheets arestored and transported in rolls. The heating of the roofing felt sheetsis typically carried out by use of propane gas burners.

When the flame, which has a typical temperature of 1000°-1300° C., isdirected towards the plastic film-coated adhesive layer, the plasticfilm decomposes and burns away and the adhesive layer is activated.However, the use of such gas burners is associated with a certain firehazard as sometimes the support or other parts of the roof constructionmay catch fire.

The noted flame heating is further associated with the drawback that thedecomposition of the plastic film is often incomplete and thereforeareas remain where the adhesive layer is covered with film residues and,as a consequence, the desired adhesion is not obtained. DK patentpublication No. 150 586 B discloses a process for producing a bituminouscoating on a support, provided with pressure equalization zones. In thisknown process a bituminous sheet material which, on the adhesive side,is provided with rows of projections of an adhesive consisting of amixture of bitumen and a thermoplastic elastomer, is adhered to thesupport. These rows are typically spaced apart about 30 mm and theprojections have a maximum length of 50 mm, a typical width of 15 mm anda height of 1-3 mm.

The formation of these projections on the bituminous sheet material iseffected by producing initially a sand-strewn bituminous sheet materialand then rolling thereon the adhesive in its melted state using apattern embossing roll.

The known material is appropriate for the formation of a coating withpressure equalization zones, but it is unsuitable for the formation of afully adhered coating as, although the adhesive is heated enough for theprojection to spread, it is not possible to obtain a uniform adhesivelayer. Moreover, the known material is associated with the drawback thatit is difficult to obtain complete removal of the film described above,as a part of the film remains on top of the projections.

GB 2.146.270 A discloses a laminated roofing coating for application ina cold process and comprising a fibrous layer optionally impregnatedwith bitumen, a bituminous layer laminated on one side of the fibrouslayer, a synthetic resin layer laminated on the bituminous layer forprotection thereof, an adhesive layer partially coated on the syntheticresin layer, and a release layer laminated on the adhesive layer.

The partially covering adhesive layer may be applied the synthetic resinlayer in the form of spots, lines, stripes, or bands.

FR2.544.361 A3 discloses a roofing coasting comprising a bituminouslayer wherein a connected system of longitudinal and transverse groovesare formed, and a polyethylene film provided on the side of thebituminous layer comprising the groove system. The groove system servesto secure pressure equalization. The roofing coating may comprise one ormore supports.

The known roofing material is manufactured by applying the plastic filmonto a plane bituminous layer, and subsequently forming the grooving inboth the film and the bituminous layer simultaneously. This groovingprocess results in a material, which is unsuitable for the formation ofa fully adhered coating, since it is difficult to obtain completeremoval of the film from the bituminous layer.

SUMMARY OF THE PRESENT INVENTION

The coating material according to the invention is characterized in thata pattern of parallel grooves and intermediate unbroken ridges isprovided in the adhesive layer, the distance between adjacent groovesnot exceeding 10 mm.

The coating material according to the invention is surprisingly found topresent a variety of technical advantages.

Firstly, such a material may be used not only for forming a fullyadhered coating on a support, viz. by heating all parts of thegroove-patterned adhesive layer, but also for forming a coating whichprevents humidity and/or air under pressure in entrapped zones fromaccumulating during the application process. The latter is obtained byheating the adhesive layer in such a manner that it is adhered to thesupport in separate zones, the grooves of the nonadhered zones servingas pressure equalization channels.

As compared to the coating material disclosed in DK patent publicationNo. 150 586, the material according to the invention is moreover simplerand thus less expensive to produce, the production thereof not requiringthe application of an additional adhesive layer of a particularcomposition.

Furthermore, the groove pattern in the adhesive layer permits a vastlyenhanced heat exchange between the hot gas stream on the one side andthe plastic film and the adhesive layer on the other side when theremoval of a plastic film fixed to the adhesive layer is to be carriedout prior to adhering the material to a support. The improved heatexchange causes the removal of the plastic film to be substantiallyfaster and more efficient and the adhesive layer to be more efficientlyactivated than when the known coating material disclosed above is used.

The practical consequence is that when using a propane gas flame forheating the energy requirement is reduced.

In practice the reduced energy requirement means that it is possible toincrease the laying out rate of roofing felt having an adhesive layer,which consists primarily of bitumen, from about 1.0 m/min to about 1.4m/min, which means that the energy consumption per m is reduced fromabout 61 g g gas/m to about 45 g gas/m.

When laying out roofing felt with a 15 cm overlap, experiments inpractice have proved it possible to increase the rate from 0.8 m/min toabout 1.5 m/min, which means that the energy consumption is reduced from63 W/m to 33 W/m.

The surprisingly improved heat exchange is also expressed by the factthat, when carrying out the process according to the invention,flameless heating of the plastic film and the adhesive layer may becarried out, the flameless heating, which may, e.g., be be carried outwith an air stream having a temperature of from 200° to 800° C., havingsurprisingly proved to effect the complete removal of the plastic filmand the activation of an adhesive layer of bitumen.

The use of such a flameless gas stream of a relatively low temperatureeliminates substantially fire hazards.

The distance between the grooves in the adhesive layer is, as statedabove, no more than 10 mm, and according to a preferred embodiment thedistance is between 1 and 5 mm, which means that the grooves aresituated relatively closely to each other. The height of the projectionsas measured from the bottom of the grooves is preferably comprisedwithin the range of from 0.5 to 6 mm, and particularly preferred withina range of from 1 to 3 mm.

Preferably, the grooves in the adhesive layer extend in the longitudinaldirection of the sheet material and thus they can be produced by combingof the adhesive layer in connection with the production of the sheetmaterial when the adhesive layer is still hot and viscous.

However, these grooves may also extend perpendicularly to this directionor at any other angle relative to the longitudinal direction.

The adhesive layer may consist of usual adhesive asphalt (bitumen), butit may also contain a self-adhesive polymer or resin.

The plastic film may, e.g., have a thickness of from about 10 μm, but inpractice films with thicknesses of from 3 to 30 μm can be used.

The invention further relates to a process for producing a waterproof,bituminous coating on a support and in particular a roof covering,wherein a sheet coating material, which, on the one side is providedwith a heat activatable adhesive layer covered by a plastic film, isheated to decompose the plastic film and to activate the adhesive layerand the activated adhesive layer is pressed against the support, theprocess being characterized in that the material according to theinvention described above is used as the coating material.

A particularly preferred embodiment of the process according to theinvention is characterized in that the heating is carried out with aflameless hot air stream.

Such air stream may, e.g., be produced by electrically heating a streamof atmospheric air.

The heating may also be carried out by heat radiation, e.g., by use ofinternally heated heating means or by IR heat radiation.

DESCRIPTION OF THE FIGURE

The invention will be further described in greater detail with referenceto the accompanying figure, which represents a schematical perspectiveview of a preferred embodiment of a roofing sheet according to theinvention.

DESCRIPTION OF PREFERRED EMBODIMENT

In the FIG. 1 denotes a roofing sheet comprising a felt layer 2 and anadhesive layer 3. The adhesive layer 3 is on the inside of the sheet 1provided with grooves 4 which extend in the longitudinal direction ofthe sheet material 1. The grooved adhesive layer 3 is coated with aplastic film 5 which abuts substantially only the tops of the ridgesbetween the grooves 4.

We claim:
 1. A bituminous sheet coating material which comprises abituminous layer having opposite sides and a heat-activatable adhesivelayer covering one of said opposite sides, said adhesive layer providinga pattern of parallel grooves and intermediate unbroken ridges, saidgrooves being spaced by no more than 10 mm.
 2. A coating materialaccording to claim 1, wherein the distance between adjacent grooves isbetween 1 and 5 mm.
 3. A coating material according to claim 1, whereinthe height of the ridges as measured from the bottom of the grooves isfrom 0.5 to 6 mm.
 4. A coating material according to claim 3, whereinthe height of the grooves is from 1 to 3 mm.
 5. A coating materialaccording to claim 1, wherein the grooves extend in a longitudinaldirection of the sheet material.
 6. A coating material according toclaim 1, wherein said adhesive layer is coated by a plastic film havinga thickness of from 3 to 30 um.
 7. A process for the production of abituminous coating on a support comprising the steps of heating a sheetcoating material provided with a heat activatable adhesive layer coveredby a plastic film to decompose the plastic film and to activate theadhesive layer, and pressing the activated adhesive layer against thesupport, wherein the coating sheet material in which the adhesive layeris provided has a pattern of parallel grooves and intermediate unbrokenridges, the distance between adjacent grooves not exceeding 10 mm.
 8. Aprocess according to claim 7, wherein the distance between adjacentgrooves is from 1 to 5 mm.
 9. A process according to claim 7, whereinthe plastic film and the adhesive layer are heated with a flameless hotair stream.